A) Field of the Invention
The present invention relates to an optical disk recording method of recording data in an optical disk by preparing, for each of a plurality of disk types, data of a waveform adjustment amount to be added to a record signal in accordance with the length of the record signal. Even when data is written in an optical disk for which the waveform adjustment amount of a record signal is not prepared, even when data is written in an optical disk which cannot obtain a good record quality by using a prepared waveform adjustment amount, or even when data is written at a constant angular velocity (CAV), the waveform adjustment amount capable of obtaining a good record quality can be easily set.
B) Description of the Related Art
There are many recordable or rewritable optical disks: recordable or rewritable type CD's such as CD-R and CD-RW and recordable or rewritable type DVD's such as DVD-R, DVD+RW, DVD-RAM and DVD−RW. Even if a laser beam is driven by the same record signal, record film sensitivity and heat conduction of each optical disk become different depending upon a disk type (not a format but a record film material, a maker, a product type number, and the like under the same format). Therefore, the front and back positions of each pit and land change with the disk type and the characteristics of reproduced signals such as jitter (shift in a time axis direction) and deviation (from a normal signal length) become different. It is, therefore, necessary to adjust the time axis and the like of a record signal waveform in accordance with each disk type in order to always ensure an optimum record quality.
Conventionally, data (so-called record strategy) of a waveform adjustment amount for each disk type supplied by a maker is stored in a memory of an optical disk recorder. The waveform adjustment amount to be added to a record signal waveform includes a time axis adjustment amount, the amplitude and width of a pulse partially added to the record signal waveform, and the like. Before actual data is recorded in an optical disk, the disk type is judged and the corresponding record strategy data is read from the memory. The waveform adjustment such as a time axis adjustment of a test signal is performed by using the read record strategy. The adjusted test signal is recorded in a predetermined test record area of the optical disk at different record powers (laser powers) of a laser beam. After test recording, the test signals are reproduced to measure the signal qualities at respective record powers. The record power capable of obtaining the best reproduced signal quality is selected. Thereafter, actual record signals are recorded by setting the laser record power to the selected record power and using the read record strategy.
Newly sold disks or unknown maker disks have no record strategy stored in the memory so that the proper record strategy cannot be determined. In order to record data in such a disk, a user is forced to perform test record to determine a record strategy. In this case, high speed and bulk hardware of high cost is necessary for an optical disk recorder. In addition, an algorithm of forming a record strategy is complicated and it takes a fairly long time to form the strategy.
Even an optical disk having the record strategy stored in the memory does not provide a high record quality because of manufacture variation or if minor change or the like in the optical disk is made without notice.
In CAV recording, the record velocity changes. It is therefore difficult to set a record strategy capable of obtaining a good reproduced signal quality at each record velocity.